Image forming apparatuses are devised to form an image on a printing medium. Examples of image forming apparatuses include printers, copiers, facsimiles, the like, and devices combining at least some functions thereof.
In an electro-photographic image forming apparatus, light is irradiated to a photosensitive body charged with a predetermined electric potential to form an electrostatic latent image on the surface thereof, and developer is fed to develop the electrostatic latent image, into a visible image. The visible image, formed on the photosensitive body, is transferred to a printing medium via a transfer device. After being transferred to the printing medium, the image undergoes a fusing operation, and is thereafter discharged out of the image forming apparatus.
A color image forming apparatus may include a plurality of photosensitive bodies, a transfer belt to directly or indirectly transfer an image formed on each photosensitive body to a printing medium and transfer rollers provided to correspond to the respective photosensitive bodies and adapted to support the transfer belt.
During a printing operation, the transfer rollers may be pressed toward the photosensitive bodies. However, according to one or more operation modes implemented by the image forming apparatus, positions of some or all of the transfer rollers may be altered to be spaced apart from the photosensitive bodies. A unit for changing the positions of some or all of the transfer rollers for implementing various operation modes is thus desired.